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ALUMINUM
Aluminum is a chemical element with symbol “Al” and atomic number 13. Under normal conditions of the
Earth’s crust is a solid state metal relatively soft silvery-white, light, ductile, malleable, durable, nonmagnetic and non-flammable.
Aluminum is the most abundant metal in the earth’s crust representing 8% of its weight, the 3rd most
abundant element after oxygen and silicon.
Aluminum is found in combinations of more than 270 minerals, but its exploitation is economically viable
only in the mineral known as “bauxite”.
There are several known isotope with mass in a range from 21 to 42, but 99.9% of their occurrence is in
the isotope 27-Aluminum (13 protons and 14 neutrons), which is the only stable.
The nucleosynthesis of Aluminum arises in heavy stars when a hydrogen proton is added to magnesium
nuclei (which in turn consists of two carbon nuclear fusion) in large stars and supernovae.
Aluminum has a density of 2.7 tons/m3 (a third of the iron and copper), making it a very lightweight metal
and is useful for several applications such as transporting people and cargo. The hardness of aluminum is
low (420 MPa), which means it is easily scratched.
Both aluminum and its alloys have a crystal structure face centered which makes it highly stable until it
fuses to 660.32 ° C. These properties make it an easy metal to change its shape and to weld it.
Aluminum is highly reactive and it is very rare to find natively on the crust, so it is a very versatile, which
can constitute about 300 alloys and a lot of variants. Despite this, aluminum does not ignite instantly, so it
has many applications in handling flammable or explosive materials.
Aluminum is not soluble in water. As is exposed to air, rapidly form a layer of aluminum oxide which
makes a material highly resistant to corrosion including both pure salt water to petrochemical and other
chemical systems. This layer might even be thicken through electrolysis and oxidizing agents to resist acid
attack.
Aluminum is the 2nd metal most easily to deform by compression and the 6th most easily deformed
without stress fractures.
Aluminum is a good conductor of electricity (between 35 and 38 m / (Ω mm2)) and can become a
superconductor at 1.2 ° K. Its low electrical resistance is 2.65 x10-18 Ohm meters. It is also a good
conductor of heat (80-230 W / (m • K), so it is very useful for heat exchangers, evaporators, electrical
appliances and auto parts.
Aluminum surfaces can be extremely reflective (71% if not polished and up to 97% when polished). Thus
the waves of the electromagnetic spectrum of visible light and heat are reflected efficiently, while ionized
surfaces can be reflective or absorbent. This is why it is often used in lamps, and numerous applications
to keep buildings and cars cool during sun seasons.
An aluminum layer may reflect approximately 92% of visible light and reflect 98% of infrared radiation.
Aluminum finish reflects ultraviolet spectra between 200 and 400 nm and between 3000 and 10000 nm in
the infrared region.
Under normal conditions its magnetism is very small, so it is considered a paramagnetic metal (nonferromagnetic) making it an important material for the electrical and electronics industry.
Source : http://www.artinaid.com/2013/04/aluminum/